Increased nucleation temperature of NiSi2 in the reaction of Ni thin films with Si1-xGex

• The formation of a ternary solid solution NiSi1-xGex, instead of a mixture of NiSi and NiGe, is found during solid-state interactions between Ni and various Si1-xGex films ranging from pure Si to pure Ge. The lattice parameters of the solid solution of orthorhombic structure increase linearly with Ge content (x) as: a=5.24+0.19x Angstrom, b=3.25+0.16x Angstrom, and c=5.68+0.15x Angstrom. The specific resistivity increases from 17 muOmega cm for NiSi to 21 muOmega cm for NiSi0.71Ge0.29 and NiSi0.42Ge0.58. Although the Ge content rapidly drops from 30-60 to about 10 at. % in the solid solutions formed above 600 degreesC, the crystallographic structure remains unchanged and no NiSi2 [or Ni(Si,Ge)(2)] is found in the Si1-xGex samples even after annealing at 850 degreesC. Without Ge, the NiSi completely disappears at 750 degreesC. These results indicate a strong effect of the entropy of mixing in NiSi-NiGe on the nucleation of NiSi2.

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

stability

silicon

silicides

alloy

cosi2

phase

Physics

Fysik

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